Key systems are known in which a particular key is required to be received in a key system as to control an aspect of operation. Many different types of keys are used as, for example, keys to open locks and doors.
In the context of dispensing systems, U.S. Patent Publication US 2006/0124662 to Reynolds et al, the disclosure of which is incorporated herein by reference, teaches an electronically powered key device on a refill container to be removably compatible with a dispenser. The refill container provides a coil terminated by one of a number of capacitors and the container is received in a housing that provides a pair of coils that are in spacial relationship with the installed refill coil. By energizing the housing's coil, the other coil detects the unique electronic signature which, if acceptable, permits the dispensing system to dispense material. The system thus utilizes a near field frequency response to determine whether the refill container is compatible with the dispensing system. A mechanical latching arrangement is provided to retain the container to the housing to ensure correct positioning of the coils.
Such previously known key devices using near field frequency response suffer the disadvantage that they are relatively complex and require a number of metal coils. This is a disadvantage of precluding substantially the entirety of the key device to be manufactured from plastic material and causes difficulties in recycling.